Interactive input systems that allow users to inject input (e.g., digital ink, mouse events etc.) into an application program using an active pointer (e.g., a pointer that emits light, sound or other signal), a passive pointer (e.g., a finger, cylinder or other suitable object) or other suitable input device such as for example, a mouse, trackball or interactive tablet, are known. These interactive input systems include but are not limited to: touch systems comprising touch panels employing analog resistive or machine vision technology to register pointer input such as those disclosed in U.S. Pat. Nos. 5,448,263; 6,141,000; 6,337,681; 6,747,636; 6,803,906; 7,232,986; 7,236,162; and 7,274,356 assigned to SMART Technologies ULC of Calgary, Alberta, Canada, assignee of the subject application, the contents of which are incorporated by reference; touch systems comprising touch panels employing electromagnetic, capacitive, acoustic or other technologies to register pointer input; tablet personal computers (PCs); touch-enabled laptop PCs; personal digital assistants (PDAs); and other similar devices.
Above-incorporated U.S. Pat. No. 6,803,906 to Morrison, et al. discloses a touch system that employs machine vision to detect pointer interaction with a touch surface on which a computer-generated image is presented. A rectangular bezel or frame surrounds the touch surface and supports digital cameras at its corners. The digital cameras have overlapping fields of view that encompass and look generally across the touch surface. The digital cameras acquire images looking generally across the touch surface from different vantages and generate image data. Image data acquired by the digital cameras is processed by on-board digital signal processors to determine if a pointer exists in the captured image data. When it is determined that a pointer exists in the captured image data, the digital signal processors convey pointer characteristic data to a master controller, which in turn processes the pointer characteristic data to determine the location of the pointer in (x,y) coordinates relative to the touch surface using triangulation. The pointer coordinates are conveyed to a computer executing one or more application programs. The computer uses the pointer coordinates to update the computer-generated image that is presented on the touch surface. Pointer contacts on the touch surface can therefore be recorded as writing or drawing or used to control execution of application programs executed by the computer.
To enhance the ability to detect and recognize passive pointers brought into proximity of a touch surface in touch systems employing machine vision technology, it is known to employ illuminated bezels to illuminate generally evenly the region over the touch surface. For example, U.S. Pat. No. 6,972,401 to Akitt, et al. assigned to SMART Technologies ULC, discloses an illuminated bezel for use in a touch system such as that described in above-incorporated U.S. Pat. No. 6,803,906. The illuminated bezel emits infrared red or other suitable radiation over the touch surface that is visible to the digital cameras. As a result, in the absence of a passive pointer in the fields of view of the digital cameras, the illuminated bezel appears in captured images as a continuous bright or “white” band. When a passive pointer is brought into the fields of view of the digital cameras, the passive pointer occludes emitted radiation and appears as a dark region interrupting the bright or “white” band in captured images allowing the existence of the pointer in the captured images to be readily determined and its position triangulated. Although this illuminated bezel is effective, it is expensive to manufacture and can add significant cost to the overall touch system. It is therefore not surprising that alternative techniques to illuminate the region over touch surfaces have been considered.
U.S. Pat. No. 7,283,128 to Sato discloses a coordinate input apparatus including a light-receiving unit arranged in the coordinate input region, a retroreflecting unit arranged at the peripheral portion of the coordinate input region to reflect incident light and a light-emitting unit which illuminates the coordinate input region with light. The retroreflecting unit is a flat tape and includes a plurality of triangular prisms each having an angle determined to be equal to or less than the detection resolution of the light-receiving unit. Angle information corresponding to a point which crosses a predetermined level in a light amount distribution obtained from the light receiving unit is calculated. The coordinates of the pointer position are calculated on the basis of a plurality of pieces of calculated angle information, the angle information corresponding to light emitted by the light-emitting unit that is reflected by the pointer.
Although the use of the retroreflecting unit to reflect and direct light into the coordinate input region is less costly than employing illuminated bezels, problems with such a retroreflecting unit exist. The amount of light reflected by the retroreflecting unit is dependent on the incident angle of the light. As a result, the Sato retroreflecting unit works best when the light is normal to its retroreflecting surface. However, when the angle of incident light on the retroreflecting surface becomes larger, the performance of the retroreflecting unit degrades resulting in uneven illumination of the bezel surrounding the coordinate input region. As a result, the possibility of false pointer contacts and/or missed pointer contacts is increased. Furthermore, prior retroreflective systems require relatively rigid bezels typically constructed of an inflexible material. For systems that must be portable, for example, in a military environment, these prior art systems are unsuitable. As will be appreciated, improvements in illumination for machine vision interactive input systems are desired.
It is therefore an object of the present invention to provide a novel interactive input system and bezel therefor.